Swapping iPhones

[offcumden]

We have two household iPhones, a 6S and an SE, both in good nick. We'd simply like to swap them over, including data, phone number, apps etc.

I believe(!) I know the principles of doing this, but could anyone with experience of doing this please tell me if I've got it right?  I think these are the stages:

1. Full back up of both phones to our Macs.
2. Factory reset on each.
3. Swap SIM cards.
4. Recover each phone from the backups.

Does it matter at which point I remove the SIM cards?

Is it really that simple, or should I go to an Apple shop and ask a genius? (who'll probably try and sell me at least one new phone )

TIA

[grams]

You can only restore to a phone running the same or newer version of iOS as the phone that was backed up. This may present a problem as both phones are obsolete.

iOS doesn't care much about which SIM is in place.

[philip]

Assuming the two phones use different Apple user IDs then you also need to ensure that each ID removes any activation lock on the phone.

[offcumden]

Thank you both - I obviously need to proceed with care! The phones are running different versions of OS, which would mean that the swap would work in one direction only, so will check with Apple how to tackle that. It's true that the 6S is discontinued, but there is a current updated version of the SE.